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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fff3ffb947a56d8b6d5c47a071a5cfd3de0eb78484daf28fca7357d5d59615cb' 
  AND token = 'X1LSgpX89ue9jgiD9LXY5EbGrKi5hj1f3/QHeCeRE8o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}